Acoustic diaphragm ajtd lqtjd-speaksr combination



March 6,1928. 1,661,523

N. BALDWIN ACOUSTIC DIAPHRAGM AND LOUD SPEAKER COMBINATION Filed April 2- 1926 W INVENTOR Patented Mar. 6, 1928.

UNITED STATES NATHANIEL BALDVIIN, 0F EA$T MILL CREEK, UTAH.

ACOUSTIC DIAPHRAGM AND LGTJD-SPEAKER COMBINATION.

Application filed April 2, 1928.

The present invention appertains to loud speakers and particularly those in which large diaphragms are used withouthorns; and is an in'iprovement on the invention for which patent application was filed January cal-a, 1926, Serial No. 83297.

The principal object is to provide a diaphragm having excess pneumatic pressure on one side and to provide pneumatic means to counterbalance the excess pressure automatically.

l attain this and other objects by the mechanism illustrated in the accompanying drawing in which the figure is a section of an instrument embodying the essential features of the invention.

Numeral 1 designates a housing in which the working elements are mounted. The ring 2 secured to the inner surface of this housing near one end is provided with a projecting flange 3 which forms a seat for the diaphragm i. This diaphragm which is made of paper or other light membrane is provided at its circumference with a re-enforcing rim 5 made preferably of a strip of sheet metal folded over the edge of the diaphragm. An annular spiral compression spring 6 presses outwardly against the inclined surface 7 and against the rim 5 and tlyus causes the diaphragm i to press against the flange or seat 3 and to form an air-tight joint. 1

he other end of the housing is closed in a similar manner by a diaphragm 8 having a rim 9 and is pressed against a seat 10 by a spring 11'. The diaphragm 8, the principal object of which is to counterbalance the pneumatic pressure on the diaphragm i, may be made of rubber to serve the purpose of damping the vibrations of the operating element and also of damping the sound within the housing 1.

The operating element may be any desired form of electrically operated armature but in the present structure I en'iploy a mechanism or unit similar to that described in my patent application for telephone receiver filed October 31, 1925, Serial No. 66,037. In this unit the spool 12 containing the actuating coil is inclosed by the U-shaped polepieces 13, 13 and the armature let passing through said spool and between said polepieces without touching either is held in proper position by taut cords or wires 15, 15 and has a virtual fulcrum within said spool. Numerals 16, 16 designate the poles Serial No. 992%.

of one of the permanent magnets which make contact with the pole-pieces 13, 13. The supporting cords or wires 15, 15, are held taut by the adjustable bracket 17. These several parts are held in proper position within the housing 1 by means of a screw 18 and spacing block 19.

Mounted upon the ends of the armature 14:.is a yoke 20 made of non-magnetic sheet metal which passes around one of the polepieces and between the poles of the magnets. This yoke is perforated on either side and pins 21 and 22 are set into it. To these pins 21 and the diaphragms i and 8 respectively are connected. Loops 23 and 24: made preferably of cord are connected to the yoke 20 as shown, the cord in either loop passing over the edge of the yoke and around the pin on either side. It will be seen that this yoke constitutes a lever arm at either end of the armature.

The diaphragm 4 may be in any desired form, but in the present structure it is substantially a plane sheet having a plurality of conoidal or reinforced portions, to the centers of which are attached eyelets 25, 2 etc. which are laced to theloop 23 with a cord 26 in such way that the tension on the eyelets can be readily adjusted to equality.

The loop 94.- is connected. to the center of the diaphragm 8 and a tension spring 27 and loops 28 may be added in the connection.

Having the armature 14a adjusted in proper position it pneumatic pressiire is created within the housing 1, the force exerted upon the yoke 20 by the diaphragm t will be counterbalanced by the force exerted by diaphragm 8 and the armature 14; will remain in adjustment.

In the present structure the diaphragm 4 is intended to produce the sound and the diaphragm 8 is used a counterbalance to the diaphragm 1 and to prevent resonance, but both diaphragms may be adapted to pro duce sound if desired.

The pneumatic pressure within the lions ing 1 is obtained and regulated by a mechanism described as follower-Nu1neral 29 designates a pressure chamber which forms the base of the instrument. The upper part of this chamber is formed into a nipple 30 which is tapped into the housing 1. Upon this nipple is mounted a compressible chamber 31, the upper wall of which carries a bracket 32 which forms a valve, and a bent tube 33 leading from the pressure chamber 29 and terminating with a small orifice at the top forms the valve seat. A tube 3 leading downward from the compressible chamber 31 communicates with the atmosphere at normal pressure.

When the chamber 29 is supplied with compressed air by means of a bulb pump 35 or other means, air will flow through the tube 33 until the pressure within the housing 1 becomes sutlicient to compress the chamber 31 and close the valve 32.

As air escapes from the housing 1 by leakage the valve 32 will let in more air from the chamber 29, and so a fairly uniform pressure will be maintained within the housing 1 while the pressure in the chamber 29 diminishes from high to low. By means of a rod 336, spring 37, and screw 38 the pressure at which the valve 32 will regulate can be adjusted.

I claim 1. A loud speaker combination comprising an acoustic diaphragm having unequal pneumatic pressure on opposite sides and having the excess pressure counterbalanced by the excess pressure on another diaphragm having unequal pneumatic pressure on oppositesides, an actuating coil, tension members, an electrically operated armature supported by said tension members within the actuating coil, lever arms mounted upon said armature and means connecting said lever arms to said diaphragms.

2. A loud speaker combination comprising an acoustic diaphragm having unequal pneumatic pressure on opposite sides and having the excess pressure counterbalanced by the excess pressure on another diaphragm hav ing unequal pneumatic pressure on opposite sides, an actuating coil, tension members, an electrically operated armature supported by said tension members within the actuating coil, lever arms mounted upon said armature and means connecting said lover arms to said (,liaphragms, and means to produce and auton'iatically regulate the excess pressure for said diaphragms.

3. A loud speaker combination comprising an acoustic diaphragm l'iaving unequal pneumatic pressure on opposite sides and having the excess pressure counterbalanced by the excess pressure on another diaphragm having unequalpneumatic pressure on opposite sides, an actuating coil, tension members, an electrically operated armature supported by said tension members within the actuating coil, lever arms mounted upon said armature, a cord lacing connecting one of said lever arms to a plurality 01" eyelets attached to said acoustic diaphragm and means to connect the other lever arm to the other diaphragm, and means to produce and automatically regulate the excess pressure for said diaphragms.

l. An acoustic diaphragm having unequal pneumatic pressure on opposite sides, pneumatic means to counterbalance the excess pressure, and an electrically operated arma ture operatively connected to said diaphragm.

5. An acoustic diaphragm having unequal pneumatic pressure on opposite sides, pneumatic means to counterbalance the excess pressure, an armature operatively connected to said diaphragm and an actuating coil surrounding said armature.

6. An acoustic diaphragm having unequal pneumatic pressure on opposite sides, an auxiliary diaphragm having unequal pneumatic pressure on opposite sides and counterbalancing the excess pressure on the acoustic diaphragm, an armature operatively connected to the acoustic diaphragm and an actuating coil surrounding said armature.

7. An acoustic diaphragm having unequal pneumatic pressure on opposite sides, pneumatic means to counterbalance the excess pressure on said diaphragm, resilient means connecting said pneumatic means with said. diaphragm, and an electrically operated armature operativcly connected with said diaphragm. 7

S. An acoustic diaphragm having unequal pneumatic pressure on opposite sides, an auxiliary diaphragm having unequal pneumatic pressure on opposite sides to counter balance the exc-ss pressure on the acoustic diaphragm, resilient. means connecting said auxiliary diaphragm with said acoustic diaphragm, and an electrically operated armature operatively connected with said acoustic diaphragm.

9. An acoustic diaphragm having unequal pneumatic pressure on opposite sides, resilient means to counterbalance the excess pressure on said diaphragm, an electrically operated armature, and a plurality of connections between said armature and said diaphragm.

10. An. acoustic diaphragm lmving un equal pneumatic pressure on opposite sides, resilient means to counterbalance the excess pressure on said diaphragm, an electrically operated armature, eyelets attached to said diaphragm, and a cord lacing connecting said armature with said eyelets.

NATHANIEL BALDXVIN. 

